A Reverse-Conducting IGBT (RC-IGBT) has recently been actively developed. The RC-IGBT has an insulated gate bipolar transistor (IGBT) and a diode formed on the same substrate and has the characteristics of the both. Unfortunately, a problem may arise that in a region of the RC-IGBT where the diode and the IGBT are adjacent, the adjacent diode and IGBT cause an unintended parasitic PNP transistor in the diode region, which causes a malfunction and characteristics failure or the like.
When manufacturing of RC-IGBTs is taken into consideration, it is important to improve the characteristics of the IGBT as well as to improve the characteristics of the diode that is to be integrated.